A rectangular area of 3200 ft^2 is to be fenced off.two opposite sides will use fencing costing $1 per foot and the remaining sides will use fencing costing $2per foot.find the dimensions of the rectangular of least cost.

Feb 28th 2010, 11:13 AM

skeeter

Quote:

Originally Posted by redcherry

A rectangular area of 3200 ft^2 is to be fenced off.two opposite sides will use fencing costing $1 per foot and the remaining sides will use fencing costing $2per foot.find the dimensions of the rectangular of least cost.

let x = side length that costs $1 per ft

y = side length that cost $2 per ft

xy = 3200

C = (1)(2x) + (2)(2y)

get the cost function in terms of a single variable, take the derivative , and minimize the cost.